Traveler of the Blue Road (蒼路の旅人, Sōro no Tabibito) is the sixth novel in the Moribito series written by Nahoko Uehashi. The story is second novel within the "Tabibito" strand that features Chagum as the protagonist.

Word comes to the Mikado that Sangal's Kalsh Archipelago is about to be attacked by the Talsh Empire, and New Yogo must send aid. A fleet is dispatched to help, led by Chagum's maternal grandfather, Admiral Tosa. Meanwhile, Chagum receives a letter from Princess Saluna, whom he met in his previous travel to Sangal, that Sangal have already been overrun, and the Yogo fleet is sailing into a trap. When Chagum begs his father to recall the fleet, the Mikado becomes angry. He sends Chagum to go fix the problem himself, accompanied only by a small escort.

Since the events of the first novel in the series, Chagum, now fifteen, has become very popular with the people, leading to a rift between him and his father. Because the Mikado now has another son, Tugum (トゥグム), by his third wife, he sees this as an opportunity to eliminate Chagum, whom he considers a rival. He assigns two Hunters, Yun and Jin, to be Chagum's bodyguards, but gives them instructions to kill Chagum. Chagum's tutor, Shuga, meanwhile, separately gives Jin instructions to protect Chagum.

Chagum rendezvous with the fleet and tells his grandfather about the trap, who feels honour-bound to complete the mission. Tosa sends the entire Yogoese fleet home, save the flagship, which is sailed straight into the Sangalese fleet. Kalsh island military commander informs Tosa that Sangal have already fallen to Talsh and demands the ship to be given up without a fight. Tosa orders the crew, including Chagum disguised as an officer, to surrender and leave the ship. Tosa remains aboard and sets the ship on fire, ultimately going down with the ship. Chagum and the others are locked into a small house as war prisoners.

During the night, Yun attempts to smother Chagum, but Jin stops him and tries to organize an escape. The escape fails, resulting in Chagum's capture by a Talsh spy Hugo Arayutan, who hired a pirate ship to capture Chagum and bring him to the Talsh capital. Hugo explains that the trap for the Yogoese fleet was actually a part of his plan to lure out and capture Chagum, whom the Second Prince Raul of the Talsh Empire intends to use to take control of New Yogo without a fight. During the long journey to the South Chagum becomes friends with the pirate ship's female captain, who even teaches him swimming in the sea and diving.

The Talsh Empire is constantly expanding, but the explanation why it needs to is omitted from this novel. It annexed Old Yogo long ago (which is where Hugo is from). During Chagum's meeting with Raul, the Talsh prince explains that his duty is to take over comparatively small countries in the North, including Sangal, New Yogo, Rota, and Kanbal. Raul plans to kill the Mikado, and then have Chagum, who becomes the next Mikado, make New Yogo surrender to Talsh. Chagum agrees to the plan to avoid massacre of his people by overwhelming power of Talsh army. However, he amends the plan as to make little Tugum the Mikado and Chagum his regent.

Chagum requests the flagship crew to be released to act as a ticket for his return to New Yogo. Near Rasu Archipelago he reunites with the crew, except Yun, on board of a Sangalese ship given to them in place of the sunken flagship. Chagum has no intention to follow Raul's plan because it actually does not save his people from war, since Talsh will later recruit New Yogo people in order to invade Rota and Kanbal, which are not expected to surrender without a fight.

Chagum devises that making an alliance with Rota kingdom will make it possible to prevent Talsh invasion of New Yogo. However, the Mikado's religious stance does not allow such an alliance, and by the time Mikado is supposed to be killed by Talsh agents, it would be too late. Chagum must personally travel to Rota unnoticed by both Mikado and Talsh.

During a night, when his ship comes close to a Sangal island, Chagum jumps overboard and swims for shore. He leaves Jin written instructions about his plan. Jin must announce that Chagum committed suicide, separately informing the Mikado of a successful assassination. The book ends on a cliffhanger.